Machines for cutting a layup of flat web material or sheet material, such as a cloth pattern cutter, are well known and used extensively. This type of machine comprises a cutting table having a support surface for the sheet material, and usually includes an infeed or layup table and a take-off platform or device. The support surface, which may be a continuous or endless belt, is at least in part air-permeable, and a vacuum holddown system is disposed beneath the support surface on which the sheet material is positioned for cutting. When vacuum is applied to the material, the material is held in position on the table to perform the cutting with greater ease and accuracy. Carrier means positioned above the table moves longitudinally and transversely relative to the table, and an instrument such as a cutting knife, drilling tool, stylus, etc., is mounted to the carrier means. The machines today typically are automatically controlled such as from programmed data.
Sheet materials that can be cut on machines of this type include woven and non-woven fabrics, leather, paper, plastics, and the like. The pattern pieces are cut in a single operation by first laying the sheet material in a multi-ply stack called a layup, and then cutting the pattern pieces from the layup. Conveyorized cutting tables having a length less than the overall length of a single layup are commonly used and cut the layup in two or more sequential segments. In order to conserve energy, a zoned cutting table has been developed whereby vacuum is applied only to a limited portion of the layup where the instrument, e.g., cutting blade is operating.
In a cutting machine of this type, the cutting instrument must pass through the layup so that all patterns cut from the layup will be substantially identical. The support surface therefore should be permeable to the cutting instrument. For this purpose, bristle mats, which are air-permeable, have been used successfully as the support surface. The support surface or cutting surface of the mat comprises a plurality of vertically packed plastic bristles extending from a perforated pad or base. When a vacuum is applied to the underside of the mat, the perforations allow the vacuum to pass through the bristles and thereby hold the sheet material in place for cutting. Further, the bristles provide a permeable cutting surface so that the cutting instrument, e.g. knife, can pass through all the sheet material in the layup and into the bristle zone and move and turn freely.
A layup of sheet material such as fabric is held down on the bristle mat by vacuum during the cutting operation, and loose lint, thread, and small fragments of scrap are drawn into the mat and accumulate between the bristles and clog the perforations in the base. As a consequence, the holddown efficiency of the mat is reduced in that as the layup is cut, the sheet material will shift therefore resulting in nonuniformity. Further, this build-up of debris causes the individual bristles to bend away from the vertical plane. As the knife blade passes through the bent bristles, the blade cuts off the bristles. This causes gaps in the bristle block, which allows a greater build-up of debris and increasingly larger gaps. The sheet material sags into the gaps, and the cutting quality is impaired. If the bristles are cutoff, the square must be replaced, which is costly to the operator.
It therefore is necessary to keep the mat clean of this debris. A sweeping mechanism for cleaning the accumulation between bristles is disclosed in U.S. Pat. No. 4,345,496 to David R. Pearl. In accordance with the teachings of that patent, the bristle mat is provided as an endless belt. During the moving mode of transferring a layup along the table, the bristle mat passes beneath the table, and a portion of the mat is contacted with a vacuum sweeper, which is controlled through a series of valves, ports and partitions. The arrangement appears to be relatively complicated, and is applicable only to an endless or continuous table.
This invention has therefore as its purpose to provide an apparatus for cleaning a support surface such as a bristle mat, used in layup cutting, whether for a fixed or endless table, and which is easy to utilize.